As shown in FIG. 8, a conventional electronic device has circuit board 1, and semiconductor device 2, such circuit components as chip component 3 and air-core coil 4, and an external circuit (not shown) that are mounted on the circuit board. The circuit components constitute an interface circuit. The external circuit is connected to semiconductor device 2 via the interface circuit. Circuit board 1 requires a large area for mounting semiconductor device 2, the interface circuit, and the external circuit.